Method for starting the combustion engine during a load shift in parallel hybrid vehicles

Abstract

A method for starting the internal combustion engine, in parallel hybrid vehicles, in which the internal combustion engine is started, during a shift under load in purely electric driving operation, by the electric machine.

1. A method of starting an internal combustion engine in a parallel hybrid vehicle in which the internal combustion engine ( 1 ) is connectable by a first clutch (K 1 ) to an electric machine ( 2 ) which is connected to a transmission ( 3 ), the method comprising the steps of:
 transmitting torque, via the first clutch (K 1 ), as a pilot torque to a speed regulator of the electric machine ( 2 ) such that torque of the internal combustion engine ( 1 ) is used as the pilot torque for the speed regulator when the first clutch (K 1 ) catches; 
 utilizing torques of an old clutch (K_alt) and a new clutch (K_neu), which are involved in a shift under load and acting upon the electric machine ( 2 ), as further pilot torques for speed regulation; 
 adapting a speed of the electric machine ( 2 ), during a speed regulation mode, for synchronization with a new gear during the shift under load; 
 engaging a first clutch (K 1 ), during the shift under load, and starting the internal combustion engine ( 1 ) during the adaptation of the speed of the electric machine ( 2 ) and during the shift under load, in a purely electrical driving operation, via the electric machine ( 2 ). 
 
     
     
       2. The method of starting the internal combustion engine according to  claim 1 , further comprising the step of adapting the speed of the electric machine ( 2 ) such that the speed (n_EM) of the electric machine ( 2 ) approaches a target speed (n_Gang_neu) with a desired gradient. 
     
     
       3. The method of starting the internal combustion engine according to  claim 2 , further comprising the step of, when the speed (n_EM) of the electric machine ( 2 ) reaches one of the target speed or a synchronous speed (n_Gang_neu) of the new gear being engaged, changing the electric machine ( 2 ) to a torque-regulated mode and completely engaging the new clutch (K_neu). 
     
     
       4. The method of starting the internal combustion engine according to  claim 1 , further comprising the step of utilizing a mass moment of inertia of the electric machine ( 2 ) as a starting torque for the internal combustion engine during an upshift. 
     
     
       5. The method of starting the internal combustion engine according to  claim 1 , further comprising the steps of
 reducing, in a traction downshift, a transmission capacity of the old clutch (K_alt) which is to be disengaged; 
 changing the electric machine ( 2 ) from a torque-controlled mode to the speed-regulation mode as soon as slip is detected at the old clutch (K_alt) being disengaged; 
 adjusted the speed of the electric machine ( 2 ) to a value higher than a synchronous speed at the new clutch (K_neu) being engaged; and 
 increasing a transmission capacity of the new clutch (K_neu) being engaged and further reducing the transmission capacity of the old clutch (K_alt) being disengaged, to facilitate a continuous load transfer to the new clutch (K_neu) being engaged, such that when the new clutch (K_neu) assumes the load, the old clutch (K_alt) being disengaged is completely disengaged and the speed of the electric machine ( 2 ) is adjusted to the synchronous speed at the new clutch (K_neu) being engaged. 
 
     
     
       6. The method of starting the internal combustion engine according to  claim 1 , further comprising the step of:
 approximately simultaneously increasing, in a thrust downshift, a transmission capacity of the new clutch (K_neu) to be engaged and reducing a transmission capacity of the old clutch (K_alt) to be disengaged; and 
 changing the electric machine ( 2 ) from a torque-controlled mode to the speed-regulation mode when the new clutch (K_neu) being engaged assumes the load and the old clutch (K_alt) being disconnected is disengaged completely, and adjusting the electric machine ( 2 ) under speed control to a synchronous speed at the new clutch (K_neu) and at approximately the same time the old clutch (K_alt) being disconnected is completely disengaged. 
 
     
     
       7. A method of starting an internal combustion engine in a parallel hybrid vehicle in which the internal combustion engine ( 1 ) is connectable by a first clutch (K 1 ) to an electric machine ( 2 ) which is connected to a transmission ( 3 ), the method comprising the steps of:
 adapting a speed of the electric machine ( 2 ), during a speed regulation mode, for synchronization with a new gear during the shift under load; 
 engaging a first clutch (K 1 ), during the shift under load, and starting the internal combustion engine ( 1 ) during the adaptation of the speed of the electric machine ( 2 ) and during the shift under load, in a purely electrical driving operation, via the electric machine ( 2 ); 
 approximately simultaneously increasing, in a traction upshift, a transmission capacity of a new clutch (K_neu) to be engaged for load transfer and reducing a transmission capacity of an old clutch (K_alt) to be disengaged; and 
 changing the electric machine ( 2 ) to a speed regulation mode when the load transfer to the new clutch (K_neu) occurs, adapting the speed of the electric machine ( 2 ) to reach a synchronous speed of the new gear being engaged such that the electric machine ( 2 ) is adjusted under speed control to either a target speed or the synchronous speed of the new gear, while approximately simultaneously completely disengaging the old clutch (K_alt). 
 
     
     
       8. A method of starting an internal combustion engine in a parallel hybrid vehicle in which the internal combustion engine ( 1 ) is connectable by a first clutch (K 1 ) to an electric machine ( 2 ) which is connected to a transmission ( 3 ), the method comprising the steps of:
 adapting a speed of the electric machine ( 2 ), during a speed regulation mode, for synchronization with a new gear during the shift under load; 
 engaging a first clutch (K 1 ), during the shift under load, and starting the internal combustion engine ( 1 ), during the adaptation of the speed of the electric machine ( 2 ) and during the shift under load, in a purely electrical driving operation, via the electric machine ( 2 ); 
 continuously reducing, in a thrust upshift, a transmission capacity of an old clutch (K_alt) to be disengaged; 
 changing the electric machine ( 2 ) from a torque-controlled mode to a speed-regulation mode as soon as slip is detected at the old clutch (K_alt) being disengaged, in which the speed of the electric machine ( 2 ) is reduced to a value below the synchronous speed at a new clutch (K_neu) to be engaged; 
 increasing a transmission capacity of the new clutch (K_neu) being engaged and reducing the transmission capacity of the old clutch (K_alt) being disengaged to transfer continuously the load to the new clutch (K_neu); and 
 completely disengaging the old clutch (K_alt) being disengaged after the load is assumed by the new clutch (K_neu) being engaged and the speed of the electric machine ( 2 ) is adjusted in the speed-regulation mode to the synchronous speed at the new clutch (K_neu) being engaged.